Abstract: In order to solve the issue of internal defect detection of magnetic tile using manual work, an analysis of fuzzy clustering bispectrum was presented for non-destructive testing of internal defect. The proposed method was based on the acoustic signal created by impacting magnetic tile. Bispectrum analysis revealed a mapping relationship between internal defect and peak distribution. Normalized bispectrum processed by a fuzzy clustering algorithm can obviously illustrate this characteristic. According to the feature, the diagonal slice of fuzzy clustering bispectrum was divided into several frequency ranges. Then identification rule was established by calculating the frequency range which contained specific amplitude of the slice. At last, the effectiveness of this method was assessed by a verification experiment and the result showed that the recognition accuracy of more than 92.5% was achieved. It was demonstrated that fuzzy clustering bispectrum can be applied to acoustic inspection for internal defect of magnetic tile.